Acquisitions (Schedule Of Business Acquisitions Revenue And Net Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Service revenue and sales	$ 2,079,583	$ 1,938,555	$ 1,782,648
Net income/(loss)	$ 319,466	219,923	205,544
HSW RR, Inc [Member]
Business Acquisition [Line Items]
Service revenue and sales		20,141	1,782
Net income/(loss)		(2,777)
Roto-Rooter, Oakland [Member]
Business Acquisition [Line Items]
Service revenue and sales		5,150	95
Net income/(loss)		231
HSW And Oakland [Member]
Business Acquisition [Line Items]
Service revenue and sales		25,291	$ 1,877
Net income/(loss)		$ (2,546)